IPv4 Subnet Calculator

Enter any IPv4 address with a CIDR prefix length (e.g. 192.168.1.0/24) to calculate all subnet properties. This tool is essential for network engineers, system administrators and anyone studying for networking certifications (CCNA, CompTIA Network+).

Calculated Values Explained

• Network Address — The first address in the subnet. Not assignable to hosts. Identifies the subnet itself.
• Subnet Mask — The dotted-decimal notation of the network mask (e.g. /24 = 255.255.255.0).
• Broadcast Address — The last address in the subnet. Used to send packets to all hosts on the subnet simultaneously. Not assignable to hosts.
• First Usable Host — Network address + 1. The first IP assignable to a host.
• Last Usable Host — Broadcast address − 1. The last IP assignable to a host.
• Host Count — Total assignable host addresses = 2^(32−prefix) − 2.
• Wildcard Mask — The bitwise inverse of the subnet mask. Used in access control lists (ACL) and OSPF configurations.

Common CIDR Subnets Reference

• /8 — Class A — 16,777,214 hosts — e.g. 10.0.0.0/8
• /16 — Class B — 65,534 hosts — e.g. 172.16.0.0/16
• /24 — Class C — 254 hosts — e.g. 192.168.1.0/24
• /28 — Small subnet — 14 hosts — common for router interfaces
• /30 — Point-to-point link — 2 hosts — router-to-router connections
• /32 — Single host — loopback, static route host entries

Private IP Ranges (RFC 1918)

Three ranges are reserved for private networks and are not routable on the public internet: 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16. These are used in home networks, corporate LANs and virtual private clouds.